CCD信号自适应采样方法的研究和实现

由于受温度变化和器件老化影响,空间遥感相机焦平面CCD信号的相位会发生变化,尤其是在高速应用领域,利用传统方法定标确定并固化的采样点参数不再适用,极大影响了图像信噪比,甚至造成图像不能正常显示。提出了一种针对空间相机焦平面CCD信号采样位置的自适应调整方法,通过实时监测CCD信号的相位变化,计算相应的采样位置调整量,并在线调整了采样时钟的相位,使CCD信号采样位置在其使用寿命期限中不同的温度环境下均能保持最佳状态,从而保证图像信噪比的稳定。实验表明:利用该方法,可以实时测定CCD信号100 ps的相位变化,并实时完成采样位置的调整,即使工作温度大范围变化,CCD信号采样位置的最佳状态也可得到有效保证。

Study and realization of adaptive sampling method for CCD signal

The phase of space remote-sensing camera CCD signal varies slightly with the temperature shift and the aging of devices. Especially in the field of high speed applications, the change of analog signal phase is non-negligible so that the sampling positions which are determined and programmed with traditional method are no longer suitable. So the SNR of image drops drastically and even in some worse cases images cannot be displayed normally. To solve the problems mentioned above, an adaptive adjustment method for sampling position of space camera CCD signal was proposed in this paper. With the proposed method, the real-time phase variation of CCD analog signal was monitored and the variation parameters of sampling position were calculated. With the calculated sampling position parameters, the circuit adjusted the phase of sampling clocks on line. The sampling position can remain in optimal state although the temperature varied in large range in the life span of the camera and the SNR of images kept high stably. Tests show that with this method, phase variation of less than 100 ps can be detected and the sampling positions keep in optimal state. So the method is effective and has a good application prospect in the field of high resolution remote sensing cameras.